Making the Connection

The original intent of this month’s column was to discuss fiber use in the smart grid, but I have found it is hard to define the smart grid. Some organizations involved in it are even dropping that name for “intelligent grid” or something similar.

One of The Fiber Optics Association directors has been working with a major utility on a training program, and one-third of the program will be about fiber optics. The rest encompasses all the electrical issues involved in generating and delivering reliable electrical power to users and how they actually consume electrical power.

Fiber optics are not new to utilities. When I was in the fiber optic test equipment business in the 1980s, my first utility customer was Nashville Electric Service. The utility was using multimode fiber to connect sensors and control equipment in substations over fiber to avoid the electrical interference and potential shock risk encountered with copper cables.

I don’t spend much time talking about sensors, but fiber optics have been used in sensors for high-voltage and large current circuits since the mid-1980s. The sensors are perfect for utilities as they operate by simply clamping them around the transmission wires and running fibers to monitoring equipment in the substation. The sensors also are capable of measuring large voltages and currents and have fast response time, all important for monitoring and controlling the utility grid.

A few years later, utilities and long-distance telephone companies (telcos) began cooperating on long-distance fiber optic links. Utilities had a valuable asset: rights-of-way, which telcos coveted. But the utilities needed communications between their facilities for voice communications and signals to control their power grid. On the other hand, telcos needed fiber optic links for their long-distance networks. By working together, the utility and the telcos both got their communications links and profited from the cooperation.

A major part of the growth of utility usage of fiber optics was optical power ground wire (OPGW), a high-voltage transmission cable with optical fiber in the center of it. It is, indeed, the perfect example of one of the advantages of optical fiber, its immunity to electrical interference. In one cable installation, power transmission and communications were both covered. Today, practically every large power transmission system uses OPGW. For example, the Sunrise PowerLink—San Diego Gas & Electric’s (SDG&E) 117-mile system under construction in Southern California—is using OPGW with 96 fibers inside the wire.

The installation of OPGW requires the skills of an electrical lineman capable of splicing high-voltage wires and the skills of an outside plant fiber optic installer to splice the fibers. Most splices are done on the ground, and splice closures are suspended from towers unless they are terminated inside regeneration huts or vaults along the right-of-way.

Besides sensing, substation controls and long-distance communications, a utility needs to monitor and control the power directly to the customer. And today, at least here in Southern California where I live, that involves not only delivering power to the customer but feeding the output of many customers’ photovoltaic solar-power systems (like my 2,500-watt systems on the roof) back into the grid. That means conversions to smart meters are another important piece of the power grid puzzle.

Some utilities, such as SDG&E, are using wireless meters that can be read by a truck driving by. Others have decided to connect customers with fiber, creating their own fiber to the home networks and either offering broadband services or using their network to deliver services for others. In some areas, this entails cooperation with telcos and CATV system operators and, in others, outright warfare.

Chattanooga, Tenn., is perhaps the best example of a utility broadband network. There you can get broadband at gigabit speeds, a first in the United States, beating out Google’s Kansas City network. The broadband network helped Chattanooga convince Volkswagen to locate a new plant there, creating thousands of new jobs.

When it comes to the smart grid, it’s impossible to generalize about the applications—or sometimes even define it. However, we can say it is a big field in the United States alone, with more than 2,000 electrical utilities combining their power into the national grid, and practically every communications technology is involved. Virtually every aspect of fiber optic technology is involved also-—sensing, communications and control, using all types of fiber in almost every application you can imagine.

For either the fiber tech or the electrical lineman interested in the smart grid, it is likely that there are areas where your expertise is required and many others where you need to learn more.

HAYES is a VDV writer and educator and the president of The Fiber Optic Association. Find him at www.jimhayes.com.